Process for treating rubber.



G. STAUNTON.

PROCESS PoR TREATING RUBBER.

APPLICATION FILED JULY 29| 1912.-

Patented Oct. 27, 1914.

l 5rd y www einen srarps GRAY STAUNTON, 0F MUSKEGON, MICHIGAN.

PROCESS FOR TREATING RUBBER.

specification' of Letters Patent.

Patented Bet.. 2'7, 15H4.

Application filed July 29, 1912. Serial No. 711,994.

To all n n/mm it may concern Be 1t known t at I,'GnA-.r SfrAUN'roN, a

citizen of the United States, residing at Muske on, in the-county ofMuskegon and State of ichigan, have invented certain new and usefulImprovements in Processes for Treating Rubber, of which the following-isa specification.

My invention relates to a process for treating rubber, and moreparticularly to the method or process of treating rubber to raise itsgrade and to (le-resinize the rubber gum.

Low grade rubberthat is rubber gum of such derivation, or so imperfectlycured, that itis soft and unduly sticky-is practically unmanageable inits original form, but it may be made commercially available by raisingits grade by an appropriate degree of vulcanization. Such low raderubbers-such as Accra flakehave eretoiore been treated to raise thegrade thereof, by vulcanization with a suitable solution of chlorid ofsult'er in bi-chlorid of carbon, said solution being mechanically mixed,as by stirring, with a plastic mass of the gum, previously made to arather stiff solution with a volatile solvent such as naphtha. Greatdiiliculty has been experienced in the practice of such old processes,however, as it is inherently di'iiicult so properly and uniformly todistribute the vulcanizing agent throughout a gum as to get a uniformproduct. Also it is almost impossible so to control the action of thevulcanizing agent as to prevent over vulcanization of the mass in Wholeor in part, the activity of the vulcanizing agent, if a little overdone,rendering the gum, or portions thereof, brittle and sub-A stantiallyworthless. Likewise where the gum contains resin the characteristicstickiness and relative impermeability of the gum makes the uniformtreatments of the mass with a resin solvent, such as caustic soda, amatter of considerable diiiiculty and of uncertainty in results.

My invention has for one of its salient objects to provide a method oftreatment overcominf these difficulties and facilitating the(le-resination of the rubber, in a fashion which insures uniform andthorough treatment of all portions of the rubber mass,

eieacious control of the duration in eacn step of the process andeconomical and eicient operation throughout.

Other and further objects of my invention will become ap arent to thoseskilled in theart from the fol owin description.

In the drawings, whereln I have shown an apparatus available forthepractice of my invention, Figure 1 is a schematic view showing adesirable lay-out ot' appliances; Fig. 2 is a sectional view of one ofthe receptacles.

In the drawing A indicates an exhauster; B a receiving tank, orreservoir; C a surface condenser; D and It] receptacles which I willterm receivers; F a materials receptacle :For the rubber; Gr, and Hreceptacles which I Will term supply receptacles, and I and J representheaters.

he exhauster may be of any suitable form of power driven vacuum pum andthe reservoir B may be any suitable iiollow receptacle of adequate size,While any practical form of condenser, preferably a surface condenser,may be employed at (l. Ilach of the receptacles D aml H is preferablyconstructcd as shown in Fig. 2, comprising a kettle-like body 5,equipped with a cover 6, suitably packed as at 7, i'o air-tight sealing,and positioned by a retaining strap 8, car- `rying a tension screw 9 forpressing the cover upon its packing. Each receptacle preferably has avalved air inlet in its top, indicated by a small letter correspondingwith the capital reference letter of the receptacle, and each receptaclepreferably has further lateral pipes 1l and l2 opening to the front andback'thereof near the top; and a bottom opening l0, connected by aT-joint to two pipes 1B and 14 which Vare connected back tothe pipes 11and l2 respectively, thereby to form a by-pass with a bottomcommunication with the receptacle. Fach of said pipes 11 and 14preferably has a controlling valve indicated by a small charactercorresponding with the reference letter' of the receptacle with theexponent 1, 2, 3, or 4, as the case may be, as shown speciically in Fig.l. f

The materials container F is suitably equipped for the retentionthereinl of the material to be treated, and `to this end I have shownstrainers 20 and 21 located in the body oit the receptacle connected bya bolt 22, the strainers leaving clearance i' spaces for the freecirculation of the fiuid treating medium above and below the material.lbor treatment of different specific materials different forms ofretaining means may, however, be employed.

1n the construction shown valved pipmg connections through receptaclesG, F, and D, condenser C and tank B to the exhauster A are provided bypipe 27, havlng valve 28, connected through a T 29, pipe 30 andcrossjoint 31 to the front pipe 1l of receptacle G, from rear pipe 12,by pipe 32 having Ts 33, 35, and 36 to the receptacle F; thence by pipe37 having cross connection '38 to receptacle D, thence by pipe 39 havingT 40 to condenser C, thence by pipe 41 having valve 42 to cross coupling43, havin one leg connected by pipe 44, having va've 45, to the topportion of the tank B, which has van exhaust connection 46 from its topthrough valve 47 and T 48 to the exhaust pump A. The coupling 43 hasanother connection 49 through valve 50 to the T 48 in exhaust connection46 beyond valve 47 and the tank B has a valved air inlet 51.

The supply receptacle H is arranged to be connected in the exhaustsystem last de scribed in lieu of the receptacle G. The front pipe 11 ofreceptacle G has connection 52 through valve 53 with cross coupling 31,and the rear pipe 12 of said receptacle has connection 54 With the T 35of pipe 32. Heater J has piping connections G0 through valve (31 to theT 3G. Receptacle E is arranged for connection in the exhaust system inlieu of or in parallel 'with' receptacle D. lipe 63 extends from crosscoupling 38hto the front pipe 11 of receptacle E,the rear pipe 12 ofwhich has connection G4 through T (55 and valve 66 by pipe G7 to theremaining opening of cross coupling 43, the T 65 having connect-ion bypipe 67, having valve G8, to the T 40 of pipe 39. Thus, material fromipe 35 may be drawn through either or iioth of the receptacles D and E,and the material passing through either receptacle D or E may be passedthrough or around the condenser C. Cross-coupling 38 has a connection7() having valve 71'With the T 7 2 to which T 33 is also connected bypipe 73 having valve 74. The T 72 has its remaining connection by pipe 75 having valve 7 to a T 77 in a return pipe or general by-pass 78, whichextends in one direction through valve 79 to the -bottom of thereservoir or tank B, and in the other direction through valve 80 to T81, one leg of which has piping connection 82 having valve 83, to the T31 while the other leg has connection 84 to a T 85 in the inlet pipe 86of a heater which has controlling its air opening a valve 87. The heateroutlet pipe 88 has valve 89 and communicates with the T 29 in pipe 30.The

by-pass -73 gives a connection between therethrough in either direction,front orv rear, by manipulation ofthe valves 1, 2, 3, and 4, appurtenantto the receptacle, accordingly as the valve 51, 45, 47 and 50 areadjusted to throw the exhauster ahead or bcliind the receptacle. Also,any receptacle may be used as the starting point of flow of fluid, bythe opening of its air valve and the closing of all valves in adirection away from the point of rarefaction. It will be observed thatin the systematic arrangement any receptacle'may be caused to deliverits fluid contents into any other receptacle of the system by the effectof the single suction device, and that heat may be applied to thematerial in transit through either of the supply receptacles, ordirectly through the materials receptacle F by proper use of the heatersI and J.

The apparatus shown may be much sim-A plified and yet be susceptible foruse in the practice of the invention, but for convenience and economyand interconnection of devices as herein described is advantageous.

Tn the treatment of rubber of low grades, and containing resin, therubber gum is preliminarily made into a stiff solution with naphtha, orother light solvent material. 'llhis is often done, in commerce, beforethe gum is shipped to the consumer, so that this step of the process isgenerally practised independcntly of the rest of the process. The @umsolution is placed in the receptacle F, between the fine stiaineis andsubmitted for a few moments to the effect of an attenuated atmosphere.To this end (all valves not mentioned beingalways assumed to be closed)valves 50, 42, d4, d3 and f2 are opened, putting the exhauster intocommunication with receptacle F. When the plastic solution of gum isthus subjected to a vacuum the expansion of the volatile solventmaterial therein seeking escape, creates within the body a multitude ofthin-walled cells and passages and changes the state of the mass to aspongy consistency, readily permeable to fluids and adording a multitudeof cell-surfaces to be acted on. To assist in this transformation of thecondition of the gum-solution from compactness to sponginess, valves 61and f3 together may be opened and closed any number of times thereby tosubject the material to successive action of hot air and the highlyrareiied atmosphere; 'llhe resultant spongy mass is then subjected tofurther treat-ment for `de-resination or change of grade.

Where the rubber gum contains resin deresination is effected by treatingwith a resin solvent the rubber guml while in the cellular or spongyplastic condition result ing from the vacuum-treatment, or successivevacuum and heat treatment described. To this end the tank Gis suppliedwith a solution of caustiesoda, or other resin sol-4 vent, and the tankH is supplied with water, or other suitable washing fluid for theremoval of the solvent. Then by opening valves g, g, f3, f2,d3,d2, andthe valves leading either through or around the condenser C and throughor around the tank B, to the pump, caustic-soda is caused to How throughand thoroughly infiltrate the spongy mass, the receiver affording areservoir for the liquid which passes through receptacle D. By openingvalves d, d 71, 74, g4, g1, 80 79 and 47 thev solution may be made toHow back from the receiving tank around the materials receptacle F tothe supply tank Gr, or by opening valves f* f1, in lieu of 71 and 7 4.,may be switched back through the rubber mass and the treatment kept upwith a relatively small supply of liquid as long as is deemed desirable.In like manner the Water from the receptacle H may be caused to pass (asthrough path defined by valves h, h4, f3, f2, e3, e2 66, 45, 47) fromthe water tank through the cellular rubber body to the receiving tank Eunder the influence of suction, and the path may be reversed byconnecting the front end of the tank H with the. general by-pass orreturn pipe 78, in a manner which will be obvious from the precedingdescription. Thus the mass is throughl washed, and the moisture may bedriven o from the rubber by application of hot air from the'heater J.

For partial vulcanization of the rubber to raise its grade (eitherwithout or following de-resination) th'e supply receptacle G is illedwith a solution of chlorid of sulfur in loi-sulfid of carbon, or othervulcanizing agent, and the receptacles H and D are supplied With a Weaksolution of ammonia or other neutralizing agent for the vulcanizingagent. Now by valve operations, as hereto fore described, the rubbermass is subjected to an attentuated atmosphere, and then the fumes ofthe sulfur solution or vulcanizing agent are admitted under control byvalve 7' as a throttle, through path defined by valves 28, g3, g2, sothat the vulcanizing agent thoroughly inltrates the spongy mass ofrubber, under the iniiuence of 'a vacuum tendency, which causes it topenetrate the entire cellular structure rapidly and uniformly. Thesulfurous fumes drawn throu h the material in tank F will be assethrough an ammonia solution in tank neutralizing the effect of thesulfur and rendering the fumes harmless to the pump and other apparatusbeyond said receiver D. Both as to quantity and time of treatment theflow of the vulcanizing agent may be controlled by the valves of thesystem, and as soon as the vulcanization is suiciently advanced thesupply of vulcanizing agent may be cut off and the ammonia solution maybe drawn through the cellular mass from the supply receptacle H. Thetreatment with the ammonia may be effected either by the introduction ofthe ammonia solution in liquid form or hot ammonia gases, derived byvdrawing air through the heater I and over the top of the ammonia b' thepath defined by valves 87, 89, 52, h1, 2, may be passed back through therubber, and where the ammonia liquld is used it mary-fI be passed backand forth from receptacle to receptacle E and vice versa, in the mannerheretofore described. When the iuid treatment is finished hot air isdrawn through the rubber mas to dry it. y

By the practice `of the process above described, the low grade rubbergum, reliminarily treated with a solvent to re uce it to a plasticconsistency, has its state modified by the expansion under suction, orheat and suction, of the volatile solvent to enlarge the` mass andrender it cellular and spongy, lthereby to expose large'thin surfacesthroughout its body to subse uent treatment, and then the vapors orliqui s are caused to act thereon in proper succession and underconstant control.

While I have herein described in some detail a particular means ofpractice of my invention it will be apparent to those skilled '1n theart that the apparatus might be greatly simplified and the processcarried on by diverse forms of apparatus without departure from myinvention and within the scope of the appended claim.

What I claim is:

The process of treating rubber gum to change its physical condition,which consists in mixing gum with a light solvent to present 'a stiffsolution, submitting the plastic mass in confinement to the eifect of ararefied atmosphere to render it cellular and spongy; admitting avulcanizing agent thereto to infiltrate the mass, and thereafter passinga neutralizing agent for the vulcanizing agent through the spongy mass.

In testimony whereof I hereunto set my hand in the presence of twowitnesses.

GRAY STAUNTON.

In the presence of- Fomin A. BAIN, MARY F. ALLEN.

